Question

6. In ancient India, 0 to 25 years of age was called
Brahmawastha and 25 to 50 was called Grahastha.
I am in Grahastha and my younger brother is also
in Grahastha such as the difference in our ages is 6
years and both of our ages are prime numbers. Also
twice my brother's age is 31 more than my age. Find the sum of our ages .
​

Answer 1

Answer:

Your age: 43

Your brother's age: 37

We have these prime numbers:

29, 31, 37, 41, 43 and 47

29 will not come. So cut that out. 31, 37, 41, 43, 47

The pairs are 31 and 37, 37 and 43, 41 and 47

First take 31.

31x2 = 62, but 62-37 = 25. So 31 and 37 is not possible.

Now take 37.

37x2 = 74 and 74-43 = 31. So 37 and 43 is possible.